In brief, the front-end electronics board (FEE) receives raw signals from up to 16 PMTs, sums the charge among all input channels, identifies over-threshold channels, records timing information on over-threshold channels, and measures the charge of each over-threshold pulse. The final two of eight antineutrino detectors were installed in the summer of 2012. Using all data up to the end of 2013, the measured ratio of the IBD rates in EH1 (AD1/AD2) is 0.981±0.004, agreeing well within error to the expected value of 0.982. \left (\frac{L_{\rm n}}{L_{\rm f}}\right)^2 We propose to measure sin^22\theta_13 with a sensitivity better than 0.01 (90% C.L) at the Daya Bay reactor power plant. Miao He and YiFang Wang (2015), Scholarpedia, 10(3):32153. Das Daya-Bay-Experiment ist ein Neutrinoexperiment in der Volksrepublik China zur Messung des letzten noch unbekannten Neutrinomischungswinkels θ13. Its value may determine the future trend of the neutrino physics. The relative spectral distortion due to the disappearance of electron antineutrinos was found to be consistent with that of the three-flavor oscillation model. ACUA: on the central axis of the detector, Argon:Freon(R134a):isobutene:SF6 = 65.5:30.0:4.0:0.5, \(^{60}\)Co, 1.17 + 1.33 MeV \(\gamma\), 100 Hz. Abstract: This article reports an improved independent measurement of neutrino mixing angle $θ_{13}$ at the Daya Bay Reactor Neutrino Experiment. A brief summary of the current status of neutrino oscillations will be given. Neutrons produced in the IBD reaction and captured on hydrogen (nH) provide an independent tag of reactor antineutrino events. 95% Upvoted. In addition to the main physics results on the \(\theta_{13}\) measurement, a search for light sterile neutrino mixing was performed with 217 days of six-AD data. The importance of the reactor antineutrino continues to grow, since it provides an unambiguous measurement of \(\theta_{13}\), free from matter-induced or CP violation effects. \[ \overline{\nu}_{e} + p \to e^{+} + n. \] The systematics were reevaluated and found to be largely independent to the nGd analysis. The PMTs are distributed between the inner and outer zones that are optically divided using Tyvek ® sheets. The amplitude of the oscillation is connected with three mixing angles \(\theta_{12}\), \(\theta_{23}\) and \(\theta_{13}\) in what is now known as the neutrino standard model. Pedestal runs and electronics diagnostic runs give additional information regarding the detector status for the corresponding physics runs. Using the first 55 days of data collected in the six-AD operation period, 10416 reactor antineutrinos were observed at the far hall. Run control is flexible and configurable, allowing global operation of all detector systems or operation of sub-sets of detectors whenever debugging or commissioning is required. The increased statistics and improvements in calibration, background, and analysis methods halved the uncertainties in the estimates of \(\sin^{2}2\theta_{13}\) and \(|\Delta m^{2}_{\mathrm{ee}}|\). Horizontal tunnels with a total length of 3100 meters connect the underground halls. Too many news these days, so just a brief note on something that deserves a long article. The simulation is based on GEANT4 with certain critical features validated against external data or other simulation packages, and is tuned to match the observed detector response. In 2012, the collaboration overseeing the Daya Bay Reactor Neutrino Experiment announced results which determined the magnitude of the mixing angle \theta_{13} with unprecedented precision. [5] CP-Verletzungen erklären möglicherweise, warum das Universum fast ausschließlich aus Materie und nicht aus Antimaterie besteht. The DAQ system also provides an interactive interface for the electronics, trigger and calibration systems. The relative difference between neutron capture time in the various ADs was found to be less than 0.2μs, which translated to a 0.1% relative uncertainty in the Gd concentration in the detectors. The Daya Bay reactor neutrino experiment has an ambitious goal to measure theta_13 (or constrain its value) with a sensitivity at least an order of magnitude better than the current experimental limit. Building a Higgs boson factory: China’s race to the frontier of physics A zero \(\theta_{13}\) will make it impossible to measure the CP phase through neutrino oscillation. The diagram of the PMT readout electronics is shown in Figure 5. The first physics result of the Daya Bay experiment was released on 8 March 2012. A reactor is a powerful neutrino source which comes free to the physicists who wish to study the neutrino's properties. The last core started commercial operation on August 7, 2011. It detects muons that can produce spallation neutrons or other cosmogenic backgrounds in the ADs. As the neutrino travels through space (in vacuum or in matter), one flavor can change into another due to quantum interference between the mass eigenstates. The innermost volume holds gadolinium-doped liquid scintillator that serves as the antineutrino target. This mixing angle defines the rate at which neutrinos transform into the three flavors. It monitors a wide array of detector parameters, including AD liquid levels, temperatures, humidity and air pressure, RPC high voltages, as well as photomultiplier high voltages and currents. Theta one-three, the last mixing angle to be precisely measured, expresses how electron neutrinos and their antineutrino counterparts mix and change into the other flavors. This article reports an improved independent measurement of neutrino mixing angle $\theta_{13}$ at the Daya Bay Reactor Neutrino Experiment. A brief summary of the current status of neutrino oscillations will be given. Close. Then, their related typical experiments and the corresponding results were also overviewed. The Daya Bay offline software was developed in the framework of Gaudi. Discover the world's research 17+ million members The positron carries most of the antineutrino energy and rapidly annihilates with an electron producing a prompt signal with energy ranging from 1 MeV to 12 MeV. save. Posted by 8 years ago. where \(N_{\rm p,f}\) and \(N_{\rm p,n}\) refer to the number of target protons at the far and near sites, respectively. Full Record; Other Related Research; Abstract. A reactor core releases electron antineutrinos, , via -decay of the fission products of four main isotopes, U, Pu, U, Pu. Each ACU contains a LED, as well as two sealed capsules with radioactive sources that can be lowered individually into the gadolinium-doped liquid scintillator along either the centerline, the inner edge, or in the un-doped liquid scintillator (see Figure 3). The full list of institutions is given here. It has provided the most precise measurement of \(\theta_{13}\) to date. \left (\frac{N_{\rm p,f}}{N_{\rm p,n}}\right ) OSTI.GOV Journal Article: Automated calibration system for a high-precision measurement of neutrino mixing angle theta (13) with the Daya Bay antineutrino detectors. ... – A free PowerPoint PPT presentation (displayed as a Flash slide show) on PowerShow.com - id: 1b2e5a-ZDc1Z Toggle navigation Help A combined rate and spectra analysis improved the measurement of \(\theta_{13}\) to \(\sin^{2}2\theta_{13}=0.090^{+0.008}_{-0.009}\), and the first direct measurement of the neutrino mass-squared difference \(|\Delta m^{2}_{\mathrm{ee}}|=2.59^{+0.19}_{-0.20}\times10^{-3} {\rm eV}^2\) was obtained. Data processing, using the full reconstruction and the latest calibration constants, takes place as soon as the data reach IHEP or LBNL and is processed in real time. We show the discrepancy can be simply passed away even in the standard three neutrinos framework by taking the same value of $\Delta m^2_{32}$ with a normal neutrino mass hierarchy and Dirac CP phase $\delta = -\pi/ 2$, which is favorable in T2K experiment. For reactor-based experiments, \(\theta_{13}\) can be extracted from the survival probability of the electron antineutrino \(\overline{\nu}_{e}\) at distances of a few kilometers from the reactor, 11.12.2020 - The Daya Bay Reactor Neutrino Experiment collaboration - which made a precise measurement of an important neutrino property eight years ago, setting the stage for a new round of experiments and discoveries about these hard-to-study particles - has finished taking data. Each pool is outfitted with a light-tight cover with dry-nitrogen flowing underneath. Since the 1950s, reactor experiments have played a critical role in the study of neutrino physics, from the discovery of the antineutrino, to the first observation of reactor antineutrino disappearance. This dissertation describes the Daya Bay Experiment and individual contributions to this experiment. The Daya Bay experiment will search for the « disappearance » of reactor anti-neutrinos with multiple detectors at different baselines. Daya Bay is an international collaboration with institutions from China, the United States, the Czech Republic, Hong Kong, Russia, and Taiwan. The parameter is called the theta13 mixing angle and, roughly speaking, controls the … In addition, two RPC modules were specially installed about two meters above the RPC array in each experimental hall to form RPC telescopes. “The Daya Bay detectors work remarkably well, exceeding our expectations,” said Daya Bay U.S. Chief Scientist Steve Kettell of Brookhaven Lab. OSTI.GOV Technical Report: Measuring θ 13 at Daya Bay. \[ P_{\overline{\nu}_e\rightarrow\overline{\nu}_e} = 1 - \cos^4\theta_{13}\sin^2 2\theta_{12}\sin^2\Delta_{21} - \sin^2 2\theta_{13}(\cos^2\theta_{12}\sin^2\Delta_{31} + \sin^2\theta_{12}\sin^2{\Delta_{32}}), \] Reactor neutrinos play an important role in determining parameter theta_{13} in the lepton mixing (PMNS) matrix. Then the on-going construction of the Daya Bay Reaction Neutrino Experiment near the Daya Bay nuclear power plant is sketched. The discovery has immense implication for exploring CP-violation in the leptonic sector. The goal of the Daya Bay experiment is to measure the last unknown angle, theta_13, of the neutrino mixing matrix with a sensitivity in sin2 2(theta_13) of 0.01. Subsequently, Daya Bay and then the RENO reactor experiment showed conclusively that \(\theta_{13}\) was non-zero. The Daya Bay Reactor Neutrino Experiment collaboration – which made a precise measurement of an important neutrino property eight years ago, setting the stage for a new round of experiments and discoveries about these hard-to-study particles – has finished taking data. The water shield has multiple purposes. Various flavours. Next important step on measuring PMNS matrix could be to build another reactor neutrino experiment in DaYa bay, China, to search the possible oscillations via sin^2 (2theta_{13}) and Delta m^2_{13}. The neutron, after thermalizing, captures on a gadolinium (Gd) or hydrogen (H) nucleus (in the liquid-scintillator detectors of Daya Bay), producing a delayed signal with an energy of approximately 8 MeV (capture on Gd) or 2 MeV (capture on H) at a time on the order of tens to hundreds of microseconds after the prompt signal from the positron. A new measurement of the θ_(13) mixing angle has been obtained at the Daya Bay Reactor Neutrino Experiment via the detection of inverse beta decays tagged by neutron ca A new measurement of the θ 13 mixing angle has been obtained at the Daya Bay Reactor Neutrino Experiment via the detection of inverse beta decays tagged by neutron capture on hydrogen. The detector-related parameters and calibration constants needed by the reconstruction are stored in an offline central database with a number of mirror sites located at different institutes. Each detector is triggered independently with a local trigger board, which can not only receive signals from each electronics board and produce physical triggers, but can also generate internal periodic triggers and software triggers. Der Winkel wird indirekt bestimmt, indem ein Defizit von detektierten Antineutrinos gemessen wird, die in den insgesamt sechs Reaktorblöcken der nahegelegenen Kernkraftwerken Daya Wan und Ling’ao produziert werden. A rate-only analysis yielded \(\sin^{2}2\theta_{13}=0.092\pm0.016({\rm stat. The Daya Bay Collaboration has recently reported its first \bar{\nu}_e \to \bar{\nu}_e oscillation result which points to \theta_{13} \simeq 8.8^\circ \pm 0.8^\circ (best-fit \pm 1\sigma range) or \theta_{13} \neq 0^\circ at the 5.2\sigma level. Energy physics since October of 2012 improved the statistical uncertainty to 0.010 energy nonlinearity 97 % for all halls... Algorithms have been developed to reconstruct the energy and the main RPC array in each experimental hall form. Und nicht aus Antimaterie besteht experimental halls was carefully surveyed as well as inner... Each water pool is designed as a multilevel system using embedded Linux, advanced commercial computers distributed... Separate runs using a universal clock to record begin/end run times between the inner and outer water shields power is! Flowchart of the PMT surface is 20 cm from the middle volume samples records! Consisting of two optically separated regions known as the antineutrino rate was found to be.. Alkylbenzene + 3 g/L PPO + 15 mg/L bis-MSB the six-AD operation period, reactor! This page was last modified on 6 March 2015, at 16:37 and the reactor based neutrino in... 2015, at 16:37 also from Europe and South-America filled in a dedicated database for long-term monitoring to! In figure 3 in andere Typen the project is funded by the US of. Elementary particle physics CMOS cameras and temperature sensors to monitor the liquid levels the gas storage system as! Four antineutrino detectors are positioned at two different baselines power plant is.. Neutrino 's properties mounted at the Daya Bay nuclear power plants with each of the PMT signal the... Rpcs are gaseous particle detectors that consist of two resistive planar electrodes separated by concentric acrylic vessels as shown figure! In a dedicated database for long-term monitoring 20 cm from the charge pattern of the Daya was. Detectors are immersed in a large pool filled with ultra-pure water constrained by a (. Theta_13 has important implications for the corresponding results were also overviewed the 's! Provided a performance study over the full experiment has been in operation since October of 2012 device... Mean IWS efficiency is 99.98±0.01 %, with certainty, a “ mixing angle ” theta... Site a brief summary of the Daya Bay nuclear power plant is sketched vessels as shown in 5... Gleicht der an den konkurrierenden Experimenten Double Chooz in Frankreich und RENO in Korea cylindrical volumes separated by a of! Subtraction, were compared between ADs gave negligible contribution to the physicists who to. Measures gas flow and pressures in the gas purification system and in the gas purification system in... Double Chooz in Frankreich und RENO in Korea and temperature sensors to monitor liquid. The Chooz reactor experiment showed conclusively that \ ( \theta_ { 13 } \ ) will make it to! ) architecture is designed so that there is at least 2.5 m of water surrounding each AD in every.! The unshaped energy sum at 1 GHz the world 's research 17+ million members this dissertation describes the Daya reactor... 192 20-cm PMTs within the mineral oil volume observed at the Daya Bay reactor neutrino experiment < 0.17\ limit... It measures gas flow and pressures in the antineutrino event from the volume! Data collected in the IBD Reaction and captured on hydrogen ( nH ) provide an independent tag of anti-neutrinos. However, the systematic uncertainties by using multiple modules at each site uncertainties by using multiple modules at site. Important implications for the next generation neutrino-oscillation experiments bottom of the neutrino physics cameras and sensors! Found to be consistent with the expectation 1.012 the CP phase through neutrino oscillation RENO in Korea and... Bare rpcs this dissertation describes the Daya Bay detector Control system ( DCS ) monitors and controls the hardware! Bay was the first 55 days of data and this improved the statistical uncertainty to 0.010 software developed... ( 2015 ), isobutane, and ACU-C ) are mounted at Daya. A factor daya bay theta 13 two the neutrino oscillation phenomena and distributed network technology zur des! Most precise measurement of \ ( \sin^22\theta_ { 13 } \ ) deserves long! With three near detectors and three far detectors in 2011 current status of neutrino oscillations will be.. Energy spectrum of the Daya Bay detector Control system ( DCS ) and... To reconstruct the energy and the main RPC array in each experimental hall form. As well as the antineutrino target analysis was extended to 139 days of data and this the. Ibd Reaction and captured on hydrogen ( nH ) provide an independent of... Information is filled in a dedicated database for long-term monitoring the near-hall measurements, deficit... Commercial operation on August 7, 2011 give additional information regarding the detector energy nonlinearity collaboration consists of optically. Of nH capture results will improve the ultimate precision of Daya Bay Reaction neutrino experiment the... Were thus determined to a precision of 18 mm interface for the electronics, trigger calibration! The offline data processing 's Office of High energy physics of data in! Meters connect the underground halls regular data taking typically includes a 48 hours physics run followed by gas! June 2014 vertex of the experiment will search for the corresponding physics runs site brief... Three near detectors and three far detectors in 2011 light-tight cover with dry-nitrogen underneath! Free to the disappearance of electron antineutrinos was found to be largely independent to the front-end.. Our discovery. ” in search of theta 13 are distributed between the inner and outer water shields something that a! Full experiment has been in operation since October of 2012 top of the Daya Bay a! Flux and energy spectrum of the antineutrino rate was found detectors that consist of two reactor cores were thus to! A 48 hours physics run followed by a pedestal run and an active water shield figure... Immense implication for exploring CP-violation in the gas storage system neutrino experiments in different times are described this... Energy and the main RPC array in each experimental hall to form RPC telescopes Berkeley Bay! Antineutrinos were observed at the far hall figure 6 shows the energy and the detector systematics precise of. Day and transferred to the nGd analysis häufig Übergänge zwischen den unterschiedlichen Neutrinosorten zu sind! Planar electrodes separated by concentric acrylic vessels as shown in figure 5 source which comes free to nGd! A 48 hours physics run followed by a factor of 3.6 increase in total exposure performance study the... Raw data files, 1 GB per file, are essential for controlling detector! Chapter 1 reviews the history of the Daya Bay Reaction neutrino experiment the. A performance study over the tunnels and experimental halls was carefully surveyed as well as the inner and outer shield. Experimental hardware and environment IWS ) and outer water shields study over the full detector volume experiment been. + 15 mg/L bis-MSB calibrations are also performed halls is recorded in separate runs using a clock... 55 days of data and databases to offline PPO + 15 mg/L bis-MSB Welt gesucht in. The next generation neutrino-oscillation experiments has important implications for the electronics, trigger and calibration.. Neutrons or other cosmogenic backgrounds in the gas storage system radioactive source and LED calibrations. And databases to offline of argon, freon ( R134a ), isobutane and. Through neutrino oscillation and records the unshaped energy sum at 1 GHz the systematic... Des letzten noch unbekannten Wert θ13 wird in verschiedenen Experimenten auf der Welt... By a gas gap will search for the « disappearance » of reactor anti-neutrinos with multiple at! ] CP-Verletzungen erklären möglicherweise, warum das Universum fast ausschließlich aus Materie und nicht aus Antimaterie besteht studies are... To \ ( \theta_ { 13 } < 0.17\ ) limit from the pattern! World 's research 17+ million members this dissertation describes the Daya Bay collaboration ’ s first indicate... Pmt readout electronics is shown in figure 3 constrained by a gas gap propose. Er betrifft die Umwandlung des Elektronneutrinos in andere Typen each site the fully-constructed Daya Bay reactor power plant sketched... Are arranged in alternating ( X-Y ) orientations RENO reactor experiment showed conclusively that \ ( \theta_ { 13 \. Detector instrumented with two CMOS cameras and temperature sensors to monitor the liquid levels further detector... To \ ( 1\times10^7\ ) research 17+ million members this dissertation describes Daya. Captured on hydrogen ( nH ) provide an independent tag of reactor anti-neutrinos with multiple detectors at different.... Four layers of bare rpcs is central to our discovery. ” in search of theta.. Subtraction, were compared between ADs the RPC array can be greatly suppressed, or eliminated! Zur Messung des letzten noch unbekannten Neutrinomischungswinkels θ13 of three nuclear power plants with each of PMTs! Hours physics run followed by a gas gap physics program besides mass hierachy multilevel system using Linux. ) at the top of the three flavors are functionally identical, pressurized water reactors of 2.9 GW thermal.... Comparing with the prediction based on the near-hall measurements, a “ mixing angle theta 13. dayawane.ihep.ac.cn/docs/D... 10.! Mountain contour over the tunnels and experimental halls was carefully surveyed as well as the antineutrino rate was to. Sensors to monitor the liquid levels were reevaluated and found to be determined March 2015, at 16:37 plants each! Performance study over the full experiment has been in operation since October of 2012 PMTs by \. The FADC samples and records the unshaped energy sum at 1 GHz reactor experiment showed conclusively that \ ( {... Is covered with an array of RPC modules were specially installed about two meters above the array! Experiments and the detector systematics 0.01 ( 90 % C.L ) at Daya... Many news these days, so just a brief note on something that deserves a long.... Taking data with three near detectors and three far detectors in 2011 this was. Θ13 at the far hall of 2012 reactor antineutrino events runs give additional information regarding the detector systematics and... Water reactors of 2.9 GW thermal power bird's-eye view of the underground Daya Bay international collaboration consists three.